To describe the cholesterol esterification systems in rat intestine, mucosal cholesterol esterase and acyl CoA: cholesterol acyltransferase (ACAT), with respect to the following: CHOLESTEROL ESTERASE: a. to define the mechanism of entry of pancreatic cholesterol esterase into mucosal cells where it functions as mucosal cholesterol esterase; b. to purify mucosal cholesterol esterase by affinity chromatography and determine directly its properties relative to pancreatic cholesterol esterase; and c. to determine the physiological substrate(s), i.e., luminal and/or biosynthesized cholesterol, for cholesterol esterase. ACAT: a. to localize ACAT in the intestine (in the absence of cholesterol esterase) with respect to proximal and distal, villous tips and crypts, and subcellular organelles; b. to determine the substrate specificity of ACAT in vitro, i.e., cholesterol specific or non-specific; and c. to determine the physiological substrate(s) for ACAT, i.e., luminal and/or biosynthesized cholesterol. To describe the intestinal transport forms for luminal and biosynthesized cholesterol.